The introduction of Model-Based Design provides several opportunities and challenges when the development of embedded software crosses the OEM/supplier interface. Traditional development processes tend to be serial, have well-defined handoff points, and lend themselves to outsourcing. But their weaknesses include a heavy reliance on written documents that are subject to misinterpretation, the discovery of problems occurring late in development, and reliance on slow and error-prone hand coding. Model-Based Design knocks down the walls between requirements, design, implementation, and testing in pursuit of cost, quality, time to market, and capacity for dealing with increased complexity. A key component of Model-Based Design is the notion of model elaboration. When all design work is done in-house, there is no confusion about who does what or who realizes the advantages of Model-Based Design. Introducing one or more suppliers into an embedded systems development process built around Model-Based Design requires careful consideration. This session details a number of OEM/supplier collaboration models that allow for the advantages of Model-Based Design to be realized and shared by both OEM and supplier.